Hot-air furnace



No. 6l0,037. Patented Aug. 30, I898.

.l. EVANS. HOT AIR FURNACE.

(Application filed JLI'L 17, 1898 w 3 Sheets-Sheet l.

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No. 610,037. Paieenzsmiz Aug. 30, I898.

J. EVANS.

HOT Km FURNACE (Application' and 3m, 17, 189m el.) 3 Sheets-$heefl 2.

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N0. 610,037. Patented Aug. 30, I898. J. EVANS.

HOT AIR FURNACE.

( Application filed Jan. 17, 1898.)

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THE cams PETERS c0. Puorouma, WASHINGTON. u. c.

JOHN EVANS, OF PHILADELPHIA, PENNSYLVANIA.

HOT-AIR FURNACE.

SPECIFICATION forming part of Letters Patent No. 610,037, dated August30, 1898. Ap licatien filed January 17, 1898. fierial No. 666,873. (Nomodelo To aZZ whom it may concern:

Be it known that I, J OHN EVANS, a citizen of the United States,residing at the 'city of Philadelphia, in the county of Philadelphia andState of Pennsylvania, have invented certain new and useful Improvementsin Hot Air Furnaces, of which the following is a specification.

My invention has relation to a hot-air furnace, and in such connectionit relates particularly to the construction and arrangement of the partscomprising such a furnace.

The principal objects of my inventionare, first, to reduce the cost ofsuch a furnace by simplifying the construction and arrange ment of theparts thereof as well as by re ducing the number of such parts;second,'to

increase the efficiency of the furnace by utilizing in an economicalmanner all the heat products and by'increasing the amount of heatarising therefrom by causing a more complete combustion of the gases andother products; third, to prevent during the open ation of the'furnacethe escape of gas, smoke, or other products of combustion into thehotair-supply conduits or tubes; fourth, to permit of the entrance ofthe cold air at a point which will prevent the entrance therewith ofdust, and, fifth, to utilize the products of combustion so that the airin the ash-pit may be warmed and to present this warmed air below andabove the grate of the furnace.

My invention, stated in general terms, consists of a hot-airfurnaceconstructed and ar ranged in a manner substantially as hereinafterdescribed and claimed.

The nature and scope of my invention will be more fully understood fromthe following description, taken in connection with the accompanyingdrawings, forming part hereof, and in which 1 Figure l is a verticalsectional view of a hot-air furnace embodying main features ofmyinvention, said section being taken on the line 1 1 of Fig. 3. Fig. Zisa transverse sectional view on theili'ne 2 2 of Fig.'1. Fig. 3

'is a similar sectional view on the line 3 3 of Fig. 1." Fig. lis avertical sectional view of the lower portion ofthe furnace, said sectionbeing taken on the line t 4; of Fig.5; and Fig. 5 is a transversesectional view on the line 5 5 of Fig. 4.

any suitable manner.

Referring to thedrawin gs, A represents the exterior casing of thefurnace supported upon I the casing A, and supported byjthe bed-plate A,substantially as hereinafter described, is

arranged a series of box-shaped castings a, one side a of each of whichis curved and rests adjacent to the fire-pot B and combustion-chamber Dof the furnace, whereas the opposite side is open and provided withflanges or wings a which when the castings are assembled togetheroverlap, as shown in Fig. 3, and form spaces 1) between the boxes,

which spaces, as hereinafter described, form flues for the passage ofthe products of coin bustion. The lower ends of these castings aconverge or taper to a flat portion a which rest in an annular groove aformed in the bed-plate A, as shown in Fig. 1, and the flat portions ofthe castings form when the parts are assembled a circular wall surrounding the base of the ash-pit E, as shown in Figs. land 5. The inner sideof the fire-pot B is provided with a ledge cl, serving as a support forthe shelld of the combustion-chamber'D, and the outer side of thesecastings a is also provided-with a ledge 6, serving as a support for thecylindrical shell 6, which serves to close the'open sides of thecastings, as shown in -Figs..1 and 3, and to form therewith hot-airconduits a The casting f of the ash-pit E is supported at its front endby an external casing A and near its rear end by a girder f, resting onthe bed-plate A or in The casing f' of the ash-pit rests at its upperedge against the inner surface of the castings a at the point where saidcastings begin to taper, and this upper edge is provided with a ledge g,serving as a support for the ring or shell B of the fire-pot B and alsofor the fire-brick g, forming the lining of the firo=pot B, as shown inFig. 1. These bricks 9 rest directly against the shell B of the fire-potB, but are provided with grooves or conduits g having an upper outlet 9into the base of the combustion-chamber D and lower inletsg com-.municating with the interior. of the ash-pit below the grate F, as shownin Figs. 1 and 3. The purpose of this arrangement will be describedhereinafter. The shell d' of the combustion-chamber D is provided with aledge m, adapted to support a funnel-shaped piece m, which serves toguide the products of combustion directly upward.

Above the castings a and preferably secured thereto by bolts is locateda cap G, shaped in cross-section as shown in Fig. 2, and it consists ofa number of box-shaped arms or projections h, the interior of whichcommunicate directly with a central chamber h, located directly aboveand surrounding the funnel-shaped piece mof the combustion-chamber D.The interior of the arms It also communicate through openings Z) wit-hthe flues b. The arms h are separated from each other bysimilarly-shaped spaces 71}, which are directly in communication withthe top of theair-chambers a, formed by the castings a, and also withthe interior of the air drum or dome A as shown in Fig. 1. The lowerends of the flues b are open, as at 5 and communicate directly with thespace f below the ash-pit E, whereas the lower ends of the air-chambersa are open, as at a, and communicate with the space (t formed betweenthe casing A and the exterior face of the castings. The bed-plate A isprovided with a number of openings a as shown in Figs. 1 and 5, topermit communication between the space a and a space (1 below thebed-plate A.

The off-take pipe II for the smoke and other products of combustion iscontinued vertically down the side of the furnace and is provided withtwo branch pipes H and H of which the pipe I-I leads directly to thecombustion-chamber D, whereas the other pipe I-l leads to the space fbelow the ashpit E,

' as illustrated in Fig. 4. The off-take pipe II extends within anextension A of the casing A. This extension A serves as a jacket for thepipe II and also as a duct for the entrance of cold air, which airenters at the top of the jacket near the top of the furnace and passesdown the pipe H to an opening A, through which it passes into the spacea below the bed-plate A.

An important feature of the present invention resides in the manner ofsecuring the castings a together to form the air-chambers a and flues b,so that the products of combustion in the lines or other parts of thefurnace cannot enter the air-chambers. To accomplish this, the castingsa, as hereinbefore described, are provided at their sides with theflanges or Wings a and at their tops with the flanges a and a Theseflanges overlap, and between the overlapped flanges a sheet or layer6612, of asbestos paper or similar fireproof material, is placed priorto the bolting of the flanges together. With this construction expansionand contraction of the castings due to changes in temperature within thefurnace may take place without disturbing the tightness of the jointthus formed, the wings or flanges sliding over each other withoutseparating.

In securing the cap G to the castings a a similar construction isemployed. In this instance the flange G' of the cap overlaps the flanged or a of the castings, and between these flanges G and a or a a layerof asbestos paper 00 is inserted before the flanges are bolted orotherwise secured together.

In operation fire is started in the tire-pot B, and the smoke andproducts of combustion enter the combustion-chamber D. From this chambera portion of the products pass through the pipe H to the off-take pipeH, near the upper end of the jacket A The remainder of the products ofcombustion ascend to the chamber h of the cap G and are deflectedthrough the interior of the arms h to the flues b, from which it passesinto the space f below the ash-pit E, heating said ash-pit, and thenpassing out through the branch pipe 11 into the off-take pipe II. Theair which is admitted to the ash-pit E through its door E is heatedbefore it enters below the grate F by the passage of products ofcombustion around the ash-pit, and a portion of this heated air in theash-pit passes through the openings or inlets g and the grooves g andthe outlets g into the combustion-chamber D, serving thereby tomaterially assist in the combustion of gases and other products in saidchamber D. The passage of the products of combustion through theflues 1) serves to highly heat the castings a, which from their closeproximity to the fire-pot and combustion-chamber are also highly heatedby the combustion of products in said fire-pot and combustion-chamber.The cold air enters at the top of the jacket A and passes down theheated off-take pipe H into the space (1 below the bed-plate A, and fromthence through the openings a into the space a between the castings andeasing A, and thence into the air-boxes a from which it is delivered tothe spaces h of the cap G and to the dome or air-drum A and escapes intothe pipes A leading to the registers. By taking the cold air in at thetopof the jacket A it will be readily understood that the air will becleaner than if taken in at the base vof the furnace, as has beenheretofore the practice, since all furnaces at their base are cloggedwith dust and ashes, the lighter particles of which will flow in withthe inrushing air. The cap G being situated directly above thecombustion-chamber is highly heated by those products of combustionwhich are conducted through the flues b, and hence the air after it isdelivered from the air-boxes a to the spaces 7L2 of thecap G is stillfurther heated by said cap G before it escapes from the drum A Byresting the flattened ends a of the castings a in the groove a of thebed-plate A a tight joint is formed without the use, as heretofore, ofcement, since a deposit of grit and IIO soot from the products ofcombustion as they pass through the space below the ash-pit will enterthe groove and serve to seal the joint therein.

Having thus described the nature and objects of my invention, what Iclaim as new, and desire to secure by Letters Patent, is-

1. In a hot-air furnace, in combination with a fire-pot and acombustion-chamber, a series of castings arranged around the fire-potand combustion-chamber, said castings being provided with flangesadapted to overlap to form alternate flues and air-boxes, the lower endof said castings tapering to a substantially flat portion to form belowthe fire-pot a circular wall, and a bed-plate arranged below thefire-pot and provided with an annular groove adapted to receive andsupport the flat portionsof the castings, substantially as and for thepurposes described.

2. In a hot air furnace, in combination with a fire-pot and acombustion-chamber, a series of castings arranged around said fire-potand combustion-chamber, said castings being provided with flangesadapted to overlap toform alternate flues and air-boxes, and a caplocated above the combustion-chamber and upon the castings, saidcaphaving its interior in communication with the combustionchamber andthe flues and its exterior in com-.

munication withv the air-boxes, substantially as and for the purposesdescribed.

3. In ahot-air furnace, in combination with the fire-pot,combustion-chamber and exterior casing, of a series of castings arrangedadjacent to the fire pot and combustionchamber and within the casing,said castings being provided with flanges adapted to overlap to formalternate flues and air-boxes, a cap located above thecombustion-chamber and having its interior in communication with saidchamber and with said flues and having its exterior in communicationwith the airboxes, and an air-drum supported by said casing andinclosing said cap, substantially as and for the purposes described.

ash-pit, substantially as and for the purposes described.

5. A hot-air furnace, comprising an exterior casing, a hollow bed-platesupporting the casing, an air-drum supported upon the easing, an ash-pitsupported within the casing above the bed-plate, a fire-pot andcombustion-chamber arranged within the casing and above the ash-pit, aseries of castings supported by the bed-plate and surrounding theash-pit, fire-pot and combustion-chamber, said castings having flangesadapted to overlap to form alternate flues and air-boxes, a capsurmounting the combustion-chamber and supported by the castings, theinterior of said cap communicating with the combustion-chamber'and theflues and the exterior of the cap communicating with the drum and theair boxes, said flues opening into the space below the ash-pit and theair-boxes communicating with the interior of the hollow bedplate, anofftake-pipe, branch pipesleading to the combustion-chamber and to thespace below the, ashpit, and a jacket surrounding the offtake-pipe andopen at its upper end for the reception of the cold air andcommunicating directly with the interior of the bed-plate, substantiallyas and for the purposes described.

In testimony whereof I have hereunto set my signature in the presence oftwo subscribing witnesses.

JOHN EVANS.

WVitnesses:

J WALTER DoUeLAss, THOMAS M. SMITH.

